This invention pertains to a system for the treatment of waste material, particularly by vitrification of the waste material. More specifically, this invention pertains to waste treatment system which enables waste treatment equipment to be readily transported to a waste site for temporary installation for the purpose of stabilizing the waste material, which may include hazardous material, low level radioactive material, or both.
Stabilization and treatment of waste material is a significant waste management problem. Although this waste management problem includes many different types of wastes, a class of wastes of particular concern is the class of mixed wastes, which contains both hazardous and low level radioactive materials. Because mixed wastes contain both hazardous and radioactive materials, they are covered by two sets of regulations, which are not inclusive of one another. The radioactive component is covered by regulations developed by the Nuclear Regulatory Commission, which establishes the requirements for low level waste landfills. The hazardous component is covered by regulations developed by the Environmental Protection Agency, which sets the requirements for hazardous waste disposal. Increased environmental consciousness has resulted in the need to stabilize many wastes, including mixed wastes, in a controlled and safe manner to avoid deleterious effects to the air and soil, and to the ground and surface water. Successful methods of stabilizing mixed wastes offer the potential for removing these wastes from hazardous regulatory control, so that only radioactive management requirements are necessary. Examples of the types of waste materials potentially harmful to the environment include low level nuclear wastes such as radioactive medical wastes, rediotracer materials, and cleanup materials from radioactive operations. Other examples include organic materials such as solvents, PCB's and dioxins which are known to be medically hazardous to human health, various heavy metals such as chromium, lead and the like, contaminated soils, waste water treatment sludge, incinerator ash, and similar materials. Mixed wastes consist of any combination of radioactive materials and hazardous materials, as described above, that are regulated as hazardous wastes.
A known system for stabilizing high level radioactive waste is the Defense Waste Processing Facility at Savannah River Site. This system treats the residues from spent fuel reprocessing operations, blends the high level radioactive waste material with glassmaking additives, melts the blend of high level radioactive waste material and the glassmaking additives to form a molten glass, thereby stabilizing the waste material, and discharges the molten glass to form a vitrified waste material. The vitrified waste material is a concentrated, inert, nonleachable material which can generally be safely stored without fear of offgassing, leaking or leaching hazardous or radioactive materials. The organic materials in such a high level radioactive waste are gassified in the vitrification process, and the gaseous streams are usually oxidized, passed through a particulate filter, and eventually released as a clean gaseous discharge. Such systems usually include large melters and extensive additional treatment facilities for preparation of the waste and feed material, and the treatment of gases and particulate matter emanating from the process. An estimated construction cost for such a system is $5 Billion U.S. dollars. A major component of these large systems is an extensive system for preventing discharge of the radioactive or hazardous waste material into the air, water or soil, exposure of personnel to the radioactive materials being treated, and additional safeguards for human-personnel.
While permanent, large scale vitrification systems are appropriate for large sources of nuclear waste, hazardous materials, or mixed waste, they are not suitable for sites with multiple waste streams or low volumes of waste material. Further, they are not appropriate for unproven waste streams or demonstration waste streams at sites where the ability to successfully stabilize waste material by vitrification has not yet been proven. These low volume and demonstration waste material sites may contain hazardous materials, low level radioactive materials, or mixed waste materials, which are a mixture of both hazardous materials and low level radioactive materials. Although most of these low volume and demonstration waste sites contain a relatively small amount of waste material to be treated, there are many more of these sites than there are of the high volume or high level radioactive waste sites.
In order to stabilize the waste material in the low volume and demonstration waste sites, and reduce the volume of waste designated for storage or disposal, a system for the treatment of the waste material must be economical, i.e., the return on the capital costs must be adequate. This precludes dedication of a fixed base waste treatment facility for most of the low volume and demonstration sites. It would be advantageous if there could be developed a system for the treatment of waste material, where the system could be transported from one waste material site to another with a minimum of erection, disassembly, transportation and reassembly costs. Such a system should be suitable for the treatment of hazardous, low level radioactive and mixed waste material without requiring extensive decontamination of the equipment prior to moving to the next low level, hazardous or mixed site. Further, such a system could be advantageously used at the demonstration sites to prove the suitability of vitrification as a method for stabilizing waste material.